Process of treating organic compounds by electrolysis.



A. PIGUET.

PROCESS FOR TREAI'ING ORGANIC COMPOUNDS BY ELECTROLYSIS.

APPLICATION FILED DEC. 3l. 1915.

Patented May 8, 1917.

ITE STATES PATENT @Fidi-@lla ALFRED PIGUET, OF'BASEL, SWITZERLAND, ASSIGNOR TO SOCIETY 0F CHEMICAL y INDUSTRY IN BASLE, 0F BASEL, SWITZERLAND.

PROCESS FOR. TREA'IING ORGANIC COMPOUNDS BY ELEC'IROUSISIS.-

Specification of Letters Patent.

Patented May 8, 2199i?.

Application led December 31, 1915. Serial No. 69,624.

To all whom t may concern:

Be it known that I, Dr. ALFRED PIGUET, chemist, a citizen of the Swiss Republic, and resident of Basel, Switzerland, have in,- vented a new and useful Process for Treating Urganic Compounds by Electrolysis, of which the following is a full, clear, and eX- act specification.

The electrolytic treatment of organic compounds, in order to subject the same to a reduction or to an oxidation, is generally effected by emulsifying 'the organic bodyin the electrolyte and subjecting. the emulsion to 'the action of the electric current at Athe cathode or the anode (active electrode). In order to obviate the disturbing inuence of the other electrode, that is to say of the electrede of opposed polarity, hitherto either diaphragms were interposed between both the electrodes or very high densities of current were employed at the said electrode of opposed polarity.

l have new found that the disturbing influence of the said electrode can still be minimized by preventing the emulsion from reaching this latter electrode. rlhis result is easily obtained by the di'erence of the specific gravity of the electrolyte and of the specific gravity of the organic body to be electrolyzed or of the solution of this latter in an indierent solvent unmixable with the electrolyte. lf care be taken to choose the said di'erence of specific weights suiciently great, it becomes easy to produce in the neighborhood of the active electrode a good emulsion which does not reach vthe other electrode.

The new process is illustrated by the following eXamples; reference being made to the accompanying diagrams: A

Figure l is a view, in section, of a form of apparatus in which the -outer vessel acts as an anode, while an inner vessel serves as a cathode; Fig. 2 is a view, in section, of a form of apparatus in which the cathode is at the top and the anode at the bottom; Fig. 3 is a view, insction, of a form of apparatus in which the anode is at the top while the cathode is at the bottgm.

vExample 1. l Reduction of m'trobenzene t5 azobenzene.,

Into the middle part of a vessel of iron, having the form of a truncated cone (Fig. l), which serves also as anode and has a conical bottom lined with a layer of cement c, is placed a cylinder k formed by several layers of iron-wire trellis acting also as cathode. The whole apparatus is filled up with soda lye of 2 to 5% and with nitrobenzene, which latter sinks to the bottom of the recipient by reason of its higher specific gravity. A small rotatory pump p turning at a high speed causes the formation of the emulsion and the slow circulation through the cylindrical cathode. At the bottom of the vessel collects a mixture of azobenzene and nitrobenzene, which is maintained continuously in circulation by the pump. rlhe reduction is achieved when all nitrobenzene has disappeared. rThe electrolysis is effected with l0 amperes per square decimeter and 2.5 to 3 volts at 85 to 95 C.

Example Z.-

Prepamtz'mt of hydmobenzene from lazobenzene.

Into a vessel c (Fi g. 2) of cement or other convenient material, is introduced at first soda lye of 30J B. gravity, in which some lead oXid has been dissolved, and afterward a solution of azobenzene' in a solvent, as for instance benzene. rIhis solution floats on the surface of the soda lye. The anode a is placed in the lower part of the vessel. At a distance of about 20 ,centimeters above the said anode is placed the cathode k formed for instance by iron-wire trellis. rlhe cathode must be placed at the limit of the two liquids (soda lye and solution of azobenzene). By a convenient vibrating movement of the cathode k the emulsion of the azobenzene solution into the soda lye is produced. This vibrating' movement is regulated in such a manner that the emulsion layer formed at the cathode is not too strong, nortoo feeble. A too strong emulsion would produce an elevationof the voltage and a too feeble emulsion would produce losses of hydrogen. The electrolysis is effected at about 900 C. with a current density of about 3 alnperes per square decimeter and a tension of 3 to 4 volts, until all the azobenzene is transformed into hydlazobenzene. It is of advantage. to collect the oxygen evolving at the anode by convenient means for instance by a wire trellis disposed above the anode in such a manner that the oxygen cannot rise to the cathode.

-lVhen the specific gravity of the electrolyte is lower than that of the emulsion', the position of the electrodes would be inverted.

Emample 3.

Preparation of kydmeobenecne from m'trobenzene.

In the electrolyzer of Fig. 2, the electrodes are inverted in such a maner that the anode comesabove the cathode. As electrolyte a solution of 2 kg. lead oxid in 800 liters soda lye of 20o B. is charged into the electrolyzer, and afterward a solution of 123 kg. ni` trobenzene in 250 liters of an indii'erent solvent of a high specific weight, for instance of dichloronaphthalene, is added. This latter solution collects at the bottom ofthe vessel. The cathode placed near the solution of nitrobenzene is put into vibration, whereby the required emulsion is produced. The electrolysis is effected at a-temperature of 85 to 95 C. The nitrobenzene is smoothly reduced to hydrazobenzene. The current density is 3 amperes per squaredecimeter and the current tension 2.5 to 3.5 volts.. With 1000 amperes the reduction lasts 120 to 150 hours. The yields are 85 to 95% of the theoretical.

Example 4. Preparation of hydrazotolueae.

In a square box of cement c (Fig. 3) are disposed horizontally twoY electrodes of metallic trellis, at a distance of about 20 centimeters each from the other. The upper electrode a serves as anode and the lower electrode as cathode. The apparatus is charged with a. solution of soda lye of 10-15 per cent. and a mixture of orthonitrotoluene with an indifferent solvent of a high specific weight, so that the said mixture sinks to the bottom of the apparatus.

By a convenient stirring, for instance by producing a circulation by a rotary pump, the emulsion is obtained. The electrolysis is effected at 80 to 1000 C. The reduction is quantitative in presence of oxids soluble in alkalis, as for instance PbO, ZnO, SnO, etc. The density of the employed current is 4.5 amperes per square decimeter and its tension 2.5 to 3 volts.

Naturally in each of the foregoing examples, the reduction can if desired be driven beyond the formation of the azo step or it can be interrupted before the hydrazo step is attained.

The same process'can be employed for the oxidation of organic substances, as shown by the following example:

Example Oxidation. of isoborneol to campkor.

at a temperature of 15 to 20 C. with a cur-v rent density of 0.5 ampere per square decimeter at the anode, until the solution, which first became green in consequence of the formation of manganate, turns again to violet.

What Iv claim is:

1. The described process for treating organic bodies by electrolysis, consisting in charging into an electrolyzer an electrolyte and the liquid organic body to be electrolyzed showing such a difference of specic gravities that near the active electrode a su'icient emulsion can be produced, which cannot reach the other electrode, producing such an emulsion and electrolyzin the contents of the electrolyzer in the usua manner.

2. rlhe described process for treating organic bodies by electrolysis consisting in charging into an electrolyzer an electrolyte and a solution of the organic body in an indifferent solvent not mixable with the electrolyte, the said electrolyte and solution of the organic body showing such a difference of their specific gravities that near the active electrode a sufiicient emulsion can be produced, which cannot reach the other electrode, producing such an emulsion and electrolyzing the contents of the velectrolyzer in the usual manner.

3. The described process for treating organic bodies by electrolysis, charging into an electrolyzer an electrolyte and the organic body to be electrolyzed having such a difference of specific ravities that a sufiicient emulsion can be pro uced in consisting in -the neighborhood of the active electrode which cannot reach the other electrode, putting the said active electrode into vibration in order to produce such an emulsion and electrolyzing the contents of the electrolyzer in the usual manner.

4. The described process for treating orgenie bodies by electrolysis, consisting in charging into the electrolyzer an electrolyte and a solution of the organic body in an indifferent solvent not mixable With the electrolyte, showing such a diference of specic gravities, that a sufficient emulsion can be produced near the active electrode Which cannot reach the said active electrode into vibration in order to produce such an emulsion and electrolyzing the contents of the electrolyzer in the usual manner.

ln Witness whereof l have hereunto signed 2t iny name this 13th day of November, 1915, in the presence of tWo subscribing Witnesses.

DR. ALFRED PlGUET.

' Witnesses:

ARNOLD ZUBER, ARMAND RITTER.

the other electrode, putting 15 

